High end SDR Clone...

[JonW]

I recently returned from another trip to China, where alongside some new product development work, I took the opportunity to investigate some SDR hardware needed for a new project I'm about to kick off.
My starting point was the usual shortlist: the AD9364-based PlutoSDR — cheap but limited; the LimeSDR — interesting custom chipset but limited frequency coverage, still pushing £600 for the privilege, and pretty hard to find; and my first choice, the USRP B210 from Ettus Research. The B210 is a serious bit of kit, built around the AD9361 — full duplex, wide instantaneous bandwidth, and a rock-solid UHD/GNU Radio ecosystem behind it. The problem is cost. Nearly £2,500 a unit, and I needed two of them plus a dedicated high-performance PC to run them both at full rate. That said, it's still cheap compared to Keysight and R&S alternatives, where the same capability costs an order of magnitude more and you'd need to sell a kidney to fund the purchase order.
After some digging I found clones at ridiculously cheap prices and, as usual, I was sceptical. The Ettus design is fully open source so anybody with a PCB house and a soldering iron can have a go — but a quick look at Digi-Key pricing showed that the main SoCs alone were already blowing the entire asking price of the clone. Something didn't add up. My assumption was the usual story: cut-price fake components, dodgy layout, marginal or zero performance. I was completely wrong.
The factory tracked down the main designer and supplier, who loaned me a unit on a sale-or-return basis. On first inspection it's immediately obvious this isn't a straight copy — it's a ground-up redesign. The most significant change is ditching the increasingly scarce and expensive Spartan-6 FPGA in favour of a Xilinx Artix-7, available in 100T or 200T configurations. Critically, this one had the full AD9361 RF front end, not the cost-reduced AD9363 that appears in some other clones — though in fairness, it's probably 99.9% the same die under the hood.
The FPGA migration was my main concern. Looking at the Ettus GitHub it's clear they spent the best part of a decade proving those modules, and porting the Verilog correctly to a different device is far from trivial. Layout at these frequencies is a known trapdoor — get it wrong and the thing simply won't work. Long story short, I was given the new binary, told where to drop it, powered the unit up, and it ran first time — booting straight up as a USRP B210. I then put it through its paces with some well-documented GNU Radio flowgraphs and verified the results on VSA running on a Keysight EXA. It met the Ettus published specification on all counts. Dynamic range came in just above 80 dB, right up against the theoretical limit for a 12-bit DAC architecture, and within a whisker of Ettus's own published SFDR figure of 78 dBc.
The cost: Ettus B210 — £2,500. Libra B220 with AD9361, Artix-7 200T, machined aluminium enclosure, cables and antennas included — $280. I bought a second unit on the spot. Both have been sitting in our environmental chambers running continuously for several days without a single issue.
Before anyone raises the obvious question — no, the Artix-7 and the AD9361 are not cloned ICs. At these process geometries it simply isn't feasible. What the Chinese engineers have done is take a freely available open-source design, upgrade the FPGA, execute a solid port of the Verilog, and clearly put real effort into the layout. The result is a unit that performs on a par with the original at a tenth of the price.

I also did some research on what's needed to run high-order modulation with Gnu Radio and some large Gnu flows on two units simultaneously.  For anyone interested Linux is still the preferred OS, mainly for its lack of bloat and the USB drivers run at full speed, which you need for high sample rates.  I looked at many options and settled on the GMTEK K10-Core I9 13900HK-32+1T cube pc for portability.  In the Uk these are about £650 but in china you can pick the same unit up for £400!  I dual-boot it with Win11 pro for some standalone software and Ubuntu for the Gnu Radio. 

Some Pics

[trastikata]

Maybe URAN-1, don't know if it will do?